A headlight for vehicles is known from EP 0 935 728 B1, which works according to the projection principle. It has a reflector, a light source unit, a lens, and an aperture device arranged between the light source unit and the lens. The light source unit consists of a gas discharge lamp which is arranged in an internal focal spot of the ellipsoidal reflector. It can be considered a point-shaped light source. The aperture device comprises an aperture shaft which is arranged perpendicularly to an optical axis of the headlight. The aperture shaft has multiple aperture edges running in the longitudinal direction, which can be moved into an upper, light-active position by means of rotation of the aperture shaft. The aperture shaft is positioned in a focal point of the lens, such that the aperture edge can be projected on the road as a light/dark boundary of the corresponding light distribution. The various different aperture edges have different contours, such that it is possible to generate a low beam light distribution, city- or foul-weather light distribution, or a highway light distribution, by way of example. Headlights using point-shaped light sources have proven successful. However, if the light source unit has a plurality of light sources which are spaced from each other, and therefore implement an emission of light from an illumination surface, the problem arises that there are optical aberrations resulting from a field of curvature of the lens. The contour set by the aperture edge cannot be precisely projected on the road.